Patch to rescue TiVo drive with errors

[terativo]

Hi folks, here is a patch to the excellent mfstools source code that allows mfsbackup and the rest to tolerate read errors. The drive in my TiVo was dying so I bought a new larger drive, wrote this patch, and successfully backed up and restored everything on the old drive to the new drive. I booted from the weaknees CD and ran these mfstools from a USB flash drive. The linux kernel spewed SCSI errors and the patched mfsbackup reported read failures -- but everything continued and it works great. Hope this helps someone else!

Code: Select all

diff -ur mfstools/lib/readwrite.c mfstools.mod/lib/readwrite.c
--- mfstools.orig/lib/readwrite.c   2007-06-07 03:19:37.000000000 -0500
+++ mfstools/lib/readwrite.c   2008-10-20 21:41:54.000000000 -0500
@@ -90,6 +90,7 @@
   loff_t result;
#endif
   int retval;
+   unsigned int orig_sector = sector;

   if (sector + count > tivo_partition_size (file))
   {
@@ -143,6 +144,37 @@
   }

   retval = read (_tivo_partition_fd (file), buf, count * 512);
+/* rescue begin */
+   if (retval < 0 && errno == EIO) {
+      int error = errno;
+      if (count == 1) {
+         fprintf(stderr, "read failure at sector %u(%#x) of %d(%#x): %s; zeroing sector\n",
+             sector, sector, count*512, count*512, strerror(errno));
+         memset(buf, 0, count * 512);
+         retval = count * 512;
+      } else {
+         int i;
+
+         fprintf(stderr, "read failure at sector %u(%#x) of %d(%#x): %s; trying sector-by-sector\n",
+             sector, sector, count*512, count*512, strerror(errno));
+         for (i = 0; i < count; i++) {
+            int r;
+
+            r = tivo_partition_read(file, (char *) buf + i * 512, orig_sector + i, 1);
+            if (r < 0) {
+               fprintf(stderr, "sector scan failed\n");
+               errno = error;
+               break;
+            }
+         }
+         if (i >= count) {
+            fprintf(stderr, "sector scan done\n");
+            retval = count * 512;
+         }
+      }
+   }
+/* rescue end */
+
   if (_tivo_partition_swab (file))
   {
      data_swab (buf, count * 512);